How to negotiate if you volunteer to be bumped from your flight, the compensation you should expect if an airline involuntarily bumps you... and a lot more.

Travel often enough, and eventually an airline will bump you and force you to take a later flight. Sometimes the bump is voluntary; sometimes, regardless of the fact you paid for a reservation and feel -- rightly so -- that you have a contract with that airline, you will get bumped involuntarily. If you get involuntarily bumped, here is what you can expect -- and here are a few ways you can try to avoid being the person bumped.

First the basics. Why do passengers get bumped? Overbooking flights is a legal and common airline practice; travelers cancel plans at the last minute, they show up late... it's a numbers game: The airline builds in a buffer of oversold seats to offset the number of people their statistical models predict will back out.

Usually the models work, and the number of overbooked passengers is equal to or less than the number of no-shows.

But sometimes it doesn't, and the airline needs to free up seats.

Here's what happens next.

You Volunteer to Be Bumped

As the Department of Transportation (DOT) says, "Almost any planeload of airline passengers includes some people with urgent travel needs and others who may be more concerned about the cost of their tickets than about getting to their destination on time. DOT rules require airlines to seek out people who are willing to give up their seats for compensation before bumping anyone involuntarily."

In practice, it's simple: A gate agent will announce to passengers in the boarding area that the flight is over-full or over-capacity (rarely have I heard them say "over-sold," since that tends to piss people off) and they are looking for volunteers to take a later flight.

Sometimes they'll announce the compensation offered; usually it's in the form of a travel voucher for a certain dollar amount. (Keep in mind the voucher can only be redeemed on a flight provided by that particular airline.) Sometimes the agents will offer $200, sometimes $400... occasionally they'll offer a free trip. Typically the amount they offer increases if no passengers are interested; in a way it's like an auction.

Don't Forget to Negotiate

Gate agents don't want to involuntarily bump passengers. While getting bumped is definitely not fun for you, it's not fun for the gate agents, either. (Imagine how fun it must be to deal with the reactions when you say, "I know you have a reservation, but you can't take this flight." Ugh.)

So if you're willing to take a later flight, see what you can get. Gate agents are allowed to negotiate as long as they stay within company guidelines, and some of those guidelines have become more generous due to recent events. (And keep in mind the DOT doesn't mandate what airlines can offer to people who volunteer to be bumped, even though a gate agent once tried to use that when he negotiated with me.)

For example, Delta gate agents were authorized to offer passengers up to $800 in flight vouchers if they volunteered to be bumped; now the limit is $2,000. Delta supervisors had a $2,000 cap on vouchers offered to bumped passengers; now they can offer up to $9,950. (Good luck getting that much, but still.)

Since you never get what you don't ask for, ask. Ask for food vouchers. Ask for hotel vouchers. Ask for cash, not an airline voucher. Ask.

I've volunteered to be bumped four times in the last year, and every time I asked for more than what was offered, I got it. Once I was traveling with a party of eight -- family vacation -- and we volunteered to be bumped to a flight leaving two hours later; we received free tickets to anywhere in the U.S. as well as meal vouchers for the airport. We were in a strong negotiating position since our party of eight freed up a chunk of oversold seats in one fell swoop.)

Just make sure you understand any restrictions or rules regarding what you receive. Some travel vouchers expire after a certain date. Some can't be used during peak travel periods.

And if you do agree to take a later flight, make sure the airline can't involuntarily bump you from that one if it turns out to be full. Years ago, that happened to me... and while I didn't go full Hulk or anything, it sucked.

The Airline Involuntarily Bumps You

If the flight is oversold and there aren't enough people willing to be bumped, you can be involuntarily bumped. Again, it's not illegal.

However, the airline is required to follow internal rules regarding who gets bumped and who does not. (The DOT doesn't mandate a specific process, but it does require each airline to actually have a process.) And the gate agent is required to provide you with a copy of those rules if you ask.

So what can you expect? That depends on the length of the delay.

If You Will Arrive Within 1 Hour of Your Original Scheduled Arrival

If the airline can get you there in no more than an hour of when your original flight would have arrived, you are entitled to no compensation.

Keep in mind the one hour refers to the new flight's scheduled arrival time, not actual -- if there is a delay along the way and it actually takes 1:15, that's too bad (for you.) The key word is "scheduled."

If You Will Arrive Between 1 and 2 Hours of Your Original Scheduled Arrival

Then the airline must pay you an amount equal to 200% of your one-way fare to your final destination that day, up to a $675 maximum.

Remember, it's one way, not the total price of your ticket. If you paid $850 for a roundtrip ticket from Dulles to LAX, you'll get $425.

Also keep in mind that for international flights, these terms apply if the next flight is scheduled to arrive between 1 and 4 hours later than your original flight.

If You Will Arrive More Than 2 Hours Later Than Your Original Scheduled Arrival

If substitute transportation is scheduled to arrive at your destination more than two hours later (or four hours for an international flight), the compensation is 400% of your one-way fare, up to a $1350 maximum).

That also applies if the airline does not make substitute travel arrangements for you at all. (Yes, they can say, "I'm sorry, but you're on your own.")

Other Tips

Ask for refunds. If you paid for certain amenities -- exit row seats, checked bags, etc -- and you do not receive those amenities on the substitute flight, the airline must refund those payments to you.

Ask for cash. Airlines typically offer free tickets or dollar-amount vouchers for future flights, but if you are involuntarily bumped you have the right to insist on getting a check instead. So ask for a check; that way the money is in your hands instead of in the form of a voucher that you may never use.

Ask for vouchers. The airline isn't required to provide other vouchers, like for airport food or other airport amenities. But they will. And they will also put you up in a hotel if you have to wait overnight. (An airline put me up in a hotel in Toronto and the desk clerk said the hotel had a standing deal with that airline for 40 rooms a night for passengers who had been bumped or whose flights had been delayed. How's that for a business model?)

And Now for the Bad News

In certain cases, the airline doesn't have to provide compensation even if you've paid for your ticket: If you miss the check-in deadline, the airline can say you have lost your reservation and therefore have lost the right to compensation if the flight is over-sold and you are bumped.

The time limit varies; most carriers expect you to be at the departure gate between 10 and 30 minutes before your flight is scheduled to depart. Others use a cut-off time of one hour. (I've never seen a gate agent start asking for volunteers an hour before a flight is scheduled to depart, though.) Other airlines only require you to be at the ticket counter by a certain time.

And of course if you've checked in online, all you have to worry about is being at the gate a little early.

The "check-in deadline" bit me once. I tried to check in online the evening before, but the airline's system was down. Oh well. I figured I'd check in the next morning, and I did, using a kiosk about 1.5 hours before my flight was scheduled to depart.

Then I got bumped. The reason? I was among the last people to check in, and the airline I was flying used that as an involuntary bump criteria. In return for being bumped I received a $310 voucher (that I didn't use before it expired) and a weary shrug from the gate agent.

How to Avoid Being Involuntarily Bumped

Airlines are allowed to set their their own boarding priorities that determine the order in which they will bump passengers on an over-sold flight.

Some airlines bump passengers with the lowest fares first; if that happens to you, there's nothing you can do about it. (Although it hardly seems fair to penalize the people who were smart enough to get the best deal.)

Most, though, bump the last passengers to check in, if only because it allows the airline to pass a little of the "blame" back on you. "If you had checked in earlier, sir," I was told, "we may not have had to bump you." (Great.)

The only real way to avoid getting involuntarily bumped is to check in early and be at the airport early. And if you're flexible about your travel plans, you can avoid being involuntarily bumped by volunteering.

Or at least saying, "I might be willing... what will you offer me?" Again, if you don't ask... you don't get.